1. Field of the Invention
The present invention relates to cutting guides, and more particularly to an annular mount for a rotary cutting tool which deploys and aligns its circular blade within the interior of a drain fitting of a sink to effect a cut at a depth substantially coinciding with the retaining ring groove in the fitting.
2. Description of the Prior Art
Those engaged in installing and/or replacing garbage disposals suspended from the underside of a sink drain fitting mounted in a kitchen sink are well aware of the difficulties associated with this task which are often compounded by the corrosion that invariably infests the very narrow spaces within which the suspending engagement is made. Simply, the corrosive environment of this very basic connection combined with the leakage limiting function thereof have resulted in a very minimal structure of the drain fitting itself that is usually replaced as a part of the repair or replacement process. Little effort is therefore devoted to save the old drain fitting as it is simply replaced as a part of a properly done repair.
In the current practice the drain fitting is fixed within the sink drain seat by an annular flange captured below the sink by a split ring seated in a ring groove formed in the neck of the drain fitting. Once so captured, a set of screws extending through the flange are advanced against the sink bottom to pull the drain fitting into an intimate sealing engagement against the seat, with the same flange then also providing the attachment structure for suspending the garbage disposal therefrom.
Of course, any removal process would ordinarily follow a reverse sequence of steps which, of necessity, entails the loosening of the tightened screws within the narrow confines beneath the sink, a manipulation that is often many years after the sink drain was first installed and now rendered substantially more difficult by long periods of corrosion. Even if somehow properly done this cumbersome removal process will invariably disrupt the original sealing contact between the drain fitting and the sink which may exhibit itself right after the job is done, or more often at some later time that may be much less convenient. Consequently good workmanship and also the natural corrosion processes compel the replacement of the simple drain fitting structure as a part of the repair, a replacement rendered most convenient by a powered cutting tool assisting in the extraction of the old fitting that may be fixed by years of corrosion in its mounted place.
In the past various cutting mechanisms and fixtures have been devised which in one way or another cut a pipe or tubing from the interior. Examples of such cutting devices may be found in the teachings of U.S. Pat. No. 4,369,573 to Vitale; U.S. Pat. No. 4,466,185 to Moutiero; U.S. Pat. No. 4,932,125 to Poveromo; U.S. Pat. No. 5,815,926 to Ekern; U.S. Pat. No. 6,508,975 to Godlewski et al.; U.S. Pat. No. 7,574,807 to Fuller et al.; and many others. Each of the foregoing, while suitable for the purposes intended, teaches a cutting tool that is deployable inside a tube to cut through the wall thereof at the point of its axial deployment and therefore little attention has been devoted to control both the radial and axial excursion of the cutting blade.
In contrast the cut that allows removal of a drain fitting mounted in a sink needs To avoid direct blade contact with the sealing surfaces of the sink and therefore must be axially aligned right over the exterior ring groove in order to release the captured flange retaining the drain fitting in the sink. Any axial departure from this deployment will either leave the ring in its capturing engagement against the flange, resulting in a useless cutting process, or in its upper ranges will expose the sink opening edges to potential cutting damage. Of course, since the replacement of garbage disposals is relatively infrequent, these attributes need to be simply and reliably implemented in an inexpensive mechanism and it is one such alignment mechanism that is disclosed herein.